3d modelling of single piles and pile groups ile group · pdf fileinteraction between piles is...
TRANSCRIPT
D-PILE GROUP
3D modelling of single piles and pile groups
In 1988, Deltares (formerly known as GeoDel )
started a research project on the behaviour of
mooring dolphins. Deltares was asked to do so by
the Dutch Ministry of Public Works. Within the
project, it was shown that many di erent methods
exist to perform calculations on single horizontally
loaded piles and pile groups. Each method has
its own advantages, but also limitations. None of
the individual methods met all the criteria of the
Dutch Ministry of Public Works. Therefore, Deltares
decided to build a computer program that would
hold several of these calculation models. The great
advantage would be that the user could switch from
one model to another, using the same input when
applicable. One of the extra criteria for this program
was that calculation times should still allow for
practical use. The resulting program D-PILE GROUP
has proved to be very useful. Previous releases of
D-PILE GROUP were called MPile. For the modelling
of pile groups two issues are important. First of
all the behaviour of individual pile(s) in their own
ground profi le is taken into account. Secondly one
has to account for the behaviour (interaction) that
each pile imposes on all other piles through the
soil and through a superstructure. These issues are
addressed in D-PILE GROUP using di erent models
that range from a standard model to more complex
models.
General
D-PILE GROUP enables the analysis of the three-dimensional
behaviour of single piles and pile groups, interacting via the pile
cap and the soil, as a function of loading. For this purpose D-PILE
GROUP o ers a unique combination of the internationally accepted
design rules of the API (American Petroleum Institute) and special
soil interaction models all within the same graphical user interface.
One of the great benefi ts of D-PILE GROUP is that switching between
di erent computational models is very easy since all relevant input
data of the previous model is kept. This fl exibility gives the user the
opportunity to choose between a fast and simple calculation and
a more complex but more accurate calculation, in a way that best
suits particular needs. The choice of models to be used depends
principally on the distance between piles. Some specifi c features
of D-PILE GROUP are:
Piles
Analysis of all pile types, both pre-defi ned standard or
userdefi ned special piles.
Pile sections with di erent properties.
Options for inclined piles (Cap; Cap Soil Interaction module and
Dynamic module).
Pile head fi xed or hinged clamp in the pile cap (freely rotating).
Soil resistance
Automated spring generation according to the API for sand
and clay layers, for static or cyclic loading, with common input
properties.
Infl uence of the pile tip resistance (elastic or elasto-plastic).
Loading
Load on the cap by moments, horizontal and vertical forces,
rotations and displacements.
Load by horizontal and vertical soil displacements (Cap module).
E ect of surcharge (Cap interaction module).
Monotonous increasing loads, load reversal and repeated (cyclic)
loads.
Dynamic load by ship collision (Dynamic module), a model for
undrained behaviour of sand.
Multiple models for the interaction between piles via the soil.
Output facilities
Graphical output of displacements, shear forces and moments
in top view.
Graphs of cap displacements and rotations versus loading.
Graphs of internal forces and soil reactions along the piles.
Automatic generation of a calculation report with tables and
graphs in rich text format. Exporting plotted data (e.g. to Excel).
D-PILE GROUP3D modelling of single piles and pile groups
Pile properties window
D-PILE GROUP comes as a standard module, which can be extended
further with other modules to fi t more advanced applications:
D-PILE GROUP Standard module (Poulos model)
Cap module (included in Standard module)
Plasti-Poulos module
Cap Soil Interaction module
Cap Layered Soil Interaction module
Dynamic module.
Standard module (Poulos module)
The standard module is intended for the analyses of single piles
and/or pile groups, using the Poulos module or the Cap module. The
Graphic User Interface allows for the input of projects, running the
analyses and provides tabular and graphical output of results both
on screen and in a report. The program provides ample options for
recalculation, using di erent pile types and fi ne-tuning of the pile
plan. In this manner a cost e cient design can easily be obtained.
Some specifi c features of the standard module will be described in
the following paragraphs:
Pile grid generator
The pile grid generator eases the input of complex pile plans for
equally spaced as well as non structured pile groups. A er the input
of piles it is possible to check each pile graphically.
Loads and soil displacement
Loads and moments can be applied on the superstructure in all
directions (x, y and z). As an alternative to force and moment
controlled loading any of the loads can be replaced by its
corresponding displacement or rotation. It is thus also possible to
apply a prescribed translation or rotation in some or all directions
(x, y and z). In the Cap module the piles can also be loaded directly
by soil displacements.
Output
Input and output tables, graphs and a report are available for
printing, viewing and for export to standard Windows applications
through the Windows clipboard. Charts are available to show
displacements, bending moments, shear forces, in x, y and z
direction for individual piles. It is also possible to view results for
Raking piles in High Speed rail viaduct
Pile grid generator
Pile properties window
displacements, bending moments and shear forces in a top view for
all piles. Cap displacements and rotations can also be visualised.
Poulos model
The Poulos model is an analytical model that takes into account
elastic soil behaviour for two soil layers. One layer along the
pile and one layer located below the pile tip. Cap interaction and
interaction between piles is taken into account. The Poulos model
is especially useful in a fi rst analysis, when only little data is
available or when the loads are small and the soil is expected to
behave mainly elastically.
Features
Elastic soil behaviour.
2 layers.
Pile-soil-pile interaction for 2 layers.
Cap module
The Cap module is included in the standard module of D-PILE GROUP.
The Cap module includes multilayered soils using linear or non linear
(elasto-plastic) springs. Cap interaction is taken into account, but
interactions between piles through soil are not taken into account.
The Cap module is therefore especially useful for single pile
analyses or pile groups with relatively large spacing. Generation
of the springs requires limited input and o ers choices ranging
from automatically created elasto-plastic springs according to
the API rules to fully user defi ned spring characteristics (linear or
elastoplastic).
Features
Elasto-plastic soil behaviour.
Layered soil (max. 99 layers).
No pile-soil-pile interaction.
Input of prescribed displacements.
Raking piles.
Plasti-Poulos module
As an extension of the Poulos model the Plasti-Poulos model
includes non linear single pile behaviour based on the analysis of a
pile in multilayered non linear soil. The behaviour of the half space
is similar to the Poulos model (elastic). The Plasti-Poulos model
can therefore be used for more accurate analyses compared to the
Poulos model, in particular when larger loads are imposed and the
system starts to show non linear e ects.
Features
Elasto-plastic soil behaviour.
Layered soil (max. 99 layers).
Pile-soil-pile interaction for 2 layers.
Poulos model
Cap model
Plasti-Poulos model
Output window for individual piles
Cap Soil Interaction module
The Cap Soil Interaction module includes single pile behaviour
based on the behaviour of multilayered non linear soils by means
of lateral and axial (elastic/elasto-plastic) springs. It allows
for input of non uniform piles while elastic soil-pile-soil group
interaction is taken into account. This module is advised for small
group spacings. It is not as fast as the above mentioned models,
but provides detailed data about forces and moments along the
length of the piles. It also allows for the use of surface loads.
Features
Elasto-plastic soil behaviour.
Layered soil (max. 99 layers).
Pile-soil-pile interaction for 1 layer.
Surface loads.
Raking piles.
Cap Layered Soil Interaction module
The Cap Layered Soil Interaction module is our most sophisticated
model and includes single pile behaviour based on the behaviour
of multilayered non linear soil modelled in continuum fi nite
elements. It allows for input of non uniform piles wh